Insects include an enormous number of organisms found all over the world. They live in all sorts of habitats ranging from the desert areas to high mountain peas. The body shape and the overall anatomy of insects are extensively modified to meet the demands required to adapt to a distinct habitat. Epilachna is one such classic beetle belonging to phylum Arthropoda and kingdom Animalia. Its class is Insecta, and the order is Coleoptera. Epilachna is generally known as ladybird beetle belonging to subfamily Epilachninae and the family Coccinellidae. There are several species known for this genus, and each carries a particular sculptured pattern of spots over the elytra. The species are classified based on the number of spots present across the elytra.
Epilachna, also known as the Mexican bean beetle, or the Hadda beetle, is recognized as an essential agricultural pest. It is an herbivorous insect that feeds on plants, unlike other ladybird beetles that feed on small insects. It is broadly distributed throughout the oriental regions and fails to survive in the dry areas. It resembles other ladybird beetles, and the number of spots varies from 14-20 over the dome-shaped elytra. Their overall color is highly variable, ranging from rusty brown to bright red to golden yellow depending upon the ecological conditions and subspecies. The body may measure 4-6 mm in length. The beetles are active from May to August in the hilly areas, while in the plains, they are active from May to September. In winters, they undergo diapauses under the crevices or cracks in the soil.
Hadda Beetle – Epilachna Characteristics features
The black and orange-spotted adults are about 5-10 millimeters long. The head, elytra (wing covers), and prothorax (first part of the middle body) are covered with small fine hairs. The elytra are comprised of 28 spots. The spots’ size and shape are variable, but only the pairs of spots by the midline of the distinct second and fourth transverse rows may connect each other—the underside of the ladybird black and orange-brown. There are three sets of orange-brown legs. Under the elytra is a set of wings used exclusively for flying. The small head is essentially pale orange and has two short antennae and a pair of compound eyes. The antennae are mostly orange-brown.
Life Stages and Annual Cycle of Epilachna
Female ladybirds lay batches of yellow eggs near infestations of prey. A larva comes out from each egg. There are around four stages (larval instars). As the larva grows, it changes skin (molts). The newly hatched larva is covered with tubercles with long seta and pale yellow. The body remains pale yellow, and the tubercles, tergites, legs, and setae turn dark grey. There are around three pairs of legs in most of babies. Larvae also use the abdomen tip for holding onto the substrate on which they are crawling and walking.
The abdomen’s tip also holds the larva to the surface during molting to another larval instar and a cocoon. When the fourth larval instar is totally grown, it connects itself to a plant’s sheltered place. The thorny skin of the larva remains attached to the pupa’s base. The pupa is wrapped in black setae. It is black except for the pale-yellow inter-segmental membranes. There are noticeable white tubular abdominal spiracles, openings to the trachea (air ducts). Adults hatch from pupae and mate. Each life stage’s length of time depends on climatic conditions and temperature, being shorter at higher temperatures.
The ladybird overwinters as adults. In spring, adults find host plants and lay eggs.
Walking and flying
This ladybird’s adult and larval stages have three pairs of legs that can be used for crawling walking. Larvae also use the abdomen tip for holding onto the substrate. Adults have lovely wings and can properly fly.
The larval and adult ladybirds feed on plant leaves. The larvae chew unique channels in one side of the leaf, leaving the epidermis on the other side of the leaf surprisingly intact.